Switch-latching mechanism



Feb. 5, 1929. 1,701,440

. H. M. CHATTO SWITCH LAIGHING MECHANISM Filed July 1, 1925 Invehtor:

Harry M. Chatto hy H Ls At torm-gy Patented Feb...5 192 9. UNITED.STATES g 4 1,101,440 PATENT OFFICE.

HARRY M. CHATTO, OF SCHENECTADY, NEW YORK, AS SIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

SWITCH-LATCHING MECHANISM.

Application filed July 1, 1925. Serial No. 40,942.

My'invention relates to electric switches,

and particularly to the latching mechanism; by means of which the switchis retained 1n,

closed circuit position. An object of my invention is the provision ofan improved, switch latching mechanism which is simple in construction,inexpensive of manufacture and which is of such a nature that while itis very sensitive it cannot be jarred out to release the switch.

My invention will be better understood from the following descriptiontaken in con nection with the accompanying drawing, and its scope willbe pointed out in the appended claims.

Figs. 1, 2 and 3 of the drawing are side elevations of a switch latchingmechanism involving my invention and showing the mechanism respectivelyin latched, partial release, and full release positions; Fig. 4 is a topview of the same; Fig. 5 is a detail on an enlarged scale; and Fig. 6shows a modification.

On the drawing the base or frame 1 has pivoted to a pair of lugs 2thereon the weighted lever 3 to one end of which are pivoted theoperating links 4. These links, portions only of which are shown, areadapted to connection with switch operating mechanism of common and wellknown form. Pivoted to two other lugs 6 on the base is the bell crank 7to one arm of which is pivoted the link 8 which is adapted tooperatively connect with the movable contacts of an oil switch. When themechanism is in the position shown by Fig. 1 the switch is closed andisheld in that position by a colla sible connection between lever 3 andbell-c1 k 7 comprising links 10 and 11 forming a toggle.v As shown inFig. 1, this toggle is slightly underset while a sec ond togglecomprising the lever 3 and the first mentioned toggle is slihtlyoverset, a suitable limiting stop not 5 ownbeing provided for thelever 3. The collapsible connection comprising links 10 and 11 ismaintained in extended'condition to hold the switch closed by thereleasable member 12 which is pivotally mounted at 13 on link 11. Theroller 14 on this member partly overlaps the end of link 10, the partsbeing so arranged that the roller tends to roll off the end of link 10and to thus cause member 12 to rotate in a clockwise direction. Thisrotative movement of member 12 is however opposed by the trigger 15which is also pivoted to link 11 at 16. This trigger while shown on thedraw ing as a bar pivoted in the middle may have any desired shape, theonly essehtial requirebearings obviously may be used if desired for vthe roller 18 and for the trigger. For returning the trigger to theposition shown in Fig. 1 after the mechanism has collapsed and foryieldingly retaining it in that position, I have shown the resettingmember 20 which is illustrated ascomprising a weight pivoted at 21't-omember 12. Obviously a spring may be used for this purpose if desired.The

weight has a flat face 22 which by engaging the fiat side of the triggerat points opposite the pivot 16 normally holds the trigger in theposition shown by Figs. 1, 3 and 5. A tripping arm 24 carrying a roller25 is adapted to be actuated by a solenoid 26 responsive to apredetermined circuit condition such for example as an overload. The armupon being raised by the solenoid strikes the trigger causing it torotate slightly, thereby releasing the member 12. i

In Fig. 2 the mechanism has been tripped and the connection comprisingthe links 10 and 11 have collapsed, permitting the initial openingmovement of the switch. Lever 3 is now free to rock to the positionshown'by Fig. 3 where the switch is full open. The lever 3 upon reachingthe position shown by Fig. 3 straightens out the connection 10 and 11and the member 12 being weighted at 28 resets itself and permits thetrigger under the influence of weight 20 to .ride under the roller 18. Adownward pull on the links 4 now will effect the closing of the switch.

Because of the fact that the rollen18 bears against the end face of thetrigger with a comparatively light pressure and they fact that this faceis smooth and concentric with the axis of rotation thereof the devicehas great sensitiveness. a ,An important feature of my invention is thefact that the trigger which is the final controlling element of thelatching mechanism when the switch is closed is balanced,

since all the forces acting upon it pass through its pivotal center. Ashas already been pointed out the axis of rotation of the trigger passesthrough its center of gravity, hence it is balanced with respect to theforce of gravity. The contact face 17 of the trigger being cylindricaland coaxial with the pivotal center of the trigger, the force'applied bythe retaining member 12 is normal to the cylindrical surface and hencepasses through the pivotal center of the trigger, also producing abalanced condition.- The third force acting on the trigger is that ofthe resetting member 20. WVhen the trigger is in reset position theresultant force of this member also passes through the pivotal center ofthe trigger. By reason of this balanced condition, the trigger isentirely unaffected by any jars to which the mechanism may be subjectedand as the trigger controls the entire mechanism the switch will not jaropen.

In the modification illustrated by Fi 6 the. releasable member 12' isconstructed without the Weighted portion 28, the weight being pivoted tothe member 12 in lieu thereof. A lighter construction of the releasablemember is therefore possible.

lVhile I have described certain embodiments only of my invention, I donot wish to be limited to the particular forms shown and described as itwill be apparent that modifications therein may be made withoutdeparting from the scope of my invention as set forth in the appendedclaims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In an electric switch, a latching mechanism comprising a releasablemember and a trigger pivotally mounted substantially at its center ofgravity for retaining the releasable member whereby jars will not causethe release of. the mechanism.

2. In an electric switch, a latching mechanism comprising a releasablemember and a pivotally mounted trigger for retaining the releasablemember, said trigger having a contact surface which is substantiallyconcentric with its pivotal center and which is adapted to be engaged bythe releasable member.

- 3. In an electric switch, a latching mechanism comprising a releasablemember and a trigger pivotally mounted substantially at its center ofgravity for retaining the releasable member, said trigger having acontact surface engaged by the releasable member which is substantiallyconcentric with its pivotal center. Y

4:. In an electric switch, a latching mechanism comprising a releasablemember having a roller mounted thereon, a trigger piv otally mounted onan axis passing through its center of gravity and provided with a faceconcentric with said axis adapted to be engaged by said roller, meansresponsive to a predetermined circuit condition for displacing thetrigger to release said member, and yielda-ble means for returning thetrigger to a position to be engaged by said member.

5. In an electric switch, latching mechanism comprising a collapsibleconnection, a releasable member having a roller thereon for controllingsaid connection, a trigger rotatably mounted on a transverse axispassing through its center of gravity. said trigger having an end faceconcentric with said axis. a weight pivoted to said member and adaptedtoengage and to normally retain the trigger in a position to have itsend face engaged by the releasable member and a member responsive' to apredetermined circuit condition for displacing the trigger.

.In witnesswhereof, I have hereunto set my hand this th day of June, 192

- HARRY M. GHATTO.

